On the moduli spaces of M(atrix)-theory compactifications

By identifying the moduli space of coupling constants in the SYM description of toroidal compactifications of M(atrix)-theory, we construct the M(atrix) description of the moduli spaces of type IIA string theory compactified on T-n. Addition of theta terms to the M(atrix) SYM produces the shift symmetries necessary to recover the correct global structure of the moduli spaces. Up to n = 3, the corresponding BPS charges transform under the proper representations of the U-duality groups, For n = 4,5, if we make the ansatz of including the BPS charges corresponding to the wrapped M-theory 5-brane, the correspondence with type IIA continues to hold. However, for n = 6, we find additional charges for which there are no obvious candidates in M(atrix)-theory, (C) 1997 Elsevier Science B.V. PACS: 11.10.Kk; 11.25.-w; 11.25.Mj; 12.90.+b.